Preparation method of solar cell, solar cell and photovoltaic module

Abstract

The invention relates to the technical field of photovoltaic cells, in particular to a preparation method of a solar cell, the solar cell and a photovoltaic module, and the preparation method of the solar cell specifically comprises the following steps: preparing a substrate; forming a passivation contact structure on the first surface of the substrate; arranging conductive paste in a first area of the second surface of the substrate; and carrying out boron diffusion doping and sintering on the first region by adopting laser, and forming an emitter layer and a second electrode in the first region. According to the preparation method of the solar cell, the solar cell and the photovoltaic module provided by the invention, the technological process can be simplified, the sheet resistance of the metal region is reduced, and the photoelectric conversion efficiency of the solar cell is improved.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic cells, and in particular to a method for preparing a solar cell, a solar cell, and a photovoltaic module. Background Art

[0002] A solar cell, also known as a "solar chip" or "photovoltaic cell," is a thin, photovoltaic semiconductor wafer that uses sunlight to generate electricity directly. As long as the illumination meets certain conditions, it can instantly output voltage and, in the presence of a circuit, generate current. However, existing solar cells have a difficult problem in reducing the sheet resistance of the metal region, making it difficult to form a good ohmic contact with the electrode, thus significantly impacting the solar cell's photoelectric conversion efficiency. Summary of the Invention

[0003] In view of this, the present application provides a method for preparing a solar cell, a solar cell, and a photovoltaic module to reduce the sheet resistance of the metal region and improve the photoelectric conversion efficiency of the solar cell.

[0004] In a first aspect, the present application provides a method for preparing a solar cell, and the method for preparing a solar cell specifically comprises the following steps: preparing a substrate; forming a passivation contact structure on the first surface of the substrate; Disposing a conductive paste on the first area of ​​the second surface of the substrate; Boron diffusion doping and sintering are performed on the first region by using laser to form an emitter layer and a second electrode in the first region.

[0005] In a possible design, the conductive paste is boron silver paste.

[0006] In one possible design, the conductive paste is silver paste; Before preparing the passivation contact structure on the first surface of the substrate, the method for preparing a solar cell further includes: disposing a boron paste in the first area of ​​the second surface of the substrate.

[0007] In one possible design, the step of doping and sintering the first region with a laser to form an emitter layer and a second electrode in the first region specifically includes: The first region is simultaneously subjected to boron diffusion doping and sintering by using a first laser, and an emitter layer is formed in the first region while a second electrode is formed.

[0008] In one possible design, the step of doping and sintering the first region with a laser to form an emitter layer and a second electrode in the first region specifically includes: performing boron diffusion doping on the first region using a second laser to form an emitter layer in the first region; The first region is sintered by using a third laser to form a second electrode in the first region.

[0009] In one possible design, providing a conductive paste in the first area of ​​the second surface of the substrate, doping and sintering the first area using a laser, and forming an emitter layer and a second electrode in the first area specifically includes: Disposing a boron slurry in the first zone; performing boron diffusion doping on the first region using a second laser to form an emitter layer in the first region; Disposing silver paste in the first area; The first region is sintered by using a third laser to form a second electrode in the first region.

[0010] In one possible design, preparing a passivation contact structure on the first surface of the substrate specifically includes: depositing a tunneling oxide layer on the first surface of the substrate; Depositing a polysilicon layer on a surface of the tunnel oxide layer facing away from the substrate; Phosphorus diffusion doping is performed on the polysilicon layer to form a doped polysilicon layer.

[0011] In one possible design, after preparing the passivation contact structure on the first surface of the substrate, the method for preparing a solar cell further includes: A metallization process is performed on a side of the doped polysilicon layer away from the tunnel oxide layer to form a first electrode.

[0012] In one possible design, after preparing the passivation contact structure on the first surface of the substrate, the method for preparing a solar cell further includes: The passivation contact structure in the fourth region of the first surface is removed.

[0013] In one possible design, after preparing the passivation contact structure on the first surface of the substrate, the method for preparing a solar cell further includes: A first passivation structure is formed on a side of the passivation contact structure facing away from the substrate and on a first surface of the substrate, and a second passivation structure is formed on a second surface of the substrate.

[0014] In one possible design, after preparing the passivation contact structure on the first surface of the substrate, the method for preparing a solar cell further includes: A first passivation structure is formed on a side of the passivation contact structure facing away from the substrate, and a second passivation structure is formed on a second surface of the substrate.

[0015] A second aspect of the embodiments of the present application provides a solar cell, which is prepared by the method for preparing a solar cell in any of the above embodiments, specifically comprising: a substrate comprising a first surface and a second surface; a passivation contact structure, the passivation contact structure being disposed on the first surface; an emitter layer, the emitter layer being disposed in the first region of the second surface; A second electrode is provided on a side of the emitter layer away from the substrate and is electrically connected to the emitter layer.

[0016] A third aspect of the present application provides a photovoltaic assembly, comprising: A battery string, wherein the battery string is formed by connecting a plurality of solar cells as described in the above embodiments; an encapsulation layer, the encapsulation layer being used to cover the surface of the battery string; A cover plate is used to cover a surface of the packaging layer away from the battery string.

[0017] In the present application, boron diffusion doping is performed only in the first region of the second surface of the substrate to form an emitter layer. The boron atom doping concentration in the first region of the second surface of the substrate is high and the square resistance is low, thereby reducing the interface contact resistance between the second electrode formed in the first region and the emitter layer, forming a good ohmic contact between the second electrode and the emitter layer, improving the carrier collection efficiency, and reducing the series resistance, reducing the power loss inside the battery, and improving the fill factor. In addition, the reduction in interface contact resistance can reduce carrier recombination and increase the open circuit voltage. However, boron diffusion doping is not performed in the second region of the second surface of the substrate. The second region of the second surface of the substrate is not doped with boron atoms, has a higher square resistance, lower Auger recombination, and better passivation effect, which can further increase the open circuit voltage of the solar cell.

[0018] Therefore, the solar cell in the embodiment of the present application can have a lower sheet resistance in the first region of the second surface of the substrate, making it easier to match with the conductive paste, thereby enabling the second electrode to form a good ohmic contact with the emitter layer, improving carrier collection efficiency, while reducing series resistance, and increasing the fill factor and open-circuit voltage. At the same time, the second region of the second surface of the substrate can have a higher sheet resistance, thereby achieving a better passivation effect, further increasing the open-circuit voltage of the solar cell, thereby achieving simultaneous optimization of electrical contact performance and surface passivation effect, and improving the photoelectric conversion efficiency of the solar cell.

[0019] Furthermore, compared to conventional boron diffusion processes, laser boron diffusion doping more easily achieves higher concentrations of boron atoms, making it easier to achieve a lower sheet resistance in the first region of the second surface of the substrate, facilitating matching with the conductive paste and further improving the photovoltaic conversion efficiency of the solar cell. Furthermore, the solar cell fabrication method of this application does not require a prior boron diffusion process, resulting in a simpler process flow and higher fabrication efficiency, which can reduce the cost of solar cell fabrication.

[0020] It should be understood that the foregoing general description and the following detailed description are merely illustrative and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0022] Figure 1 A flow chart of a method for preparing a solar cell provided in an embodiment of the present application; Figure 2 A schematic structural diagram of a substrate provided in an embodiment of the present application in a specific embodiment; Figure 3 A schematic diagram of a passivation contact structure formed on a first surface of a substrate; Figure 4 A schematic diagram of a structure for forming a tunnel oxide layer on a first surface of a substrate; Figure 5 A schematic diagram of a structure in which a polysilicon layer is formed on the side of the tunnel oxide layer facing away from the substrate; Figure 6 A schematic diagram of a passivation contact structure in which the fourth region of the first surface is removed; Figure 7 A schematic cross-sectional view of a portion of the structure of a solar cell provided in an embodiment of the present application in a specific embodiment; Figure 8 A schematic diagram of the cross-sectional structure of a solar cell provided in an embodiment of the present application in a specific embodiment; Figure 9 A schematic cross-sectional view of a portion of the structure of a solar cell provided in an embodiment of the present application in another specific embodiment; Figure 10 A schematic diagram of the cross-sectional structure of a solar cell provided in an embodiment of the present application in another specific embodiment; Figure 11 This is a schematic diagram of the structure of the photovoltaic module provided in this application.

[0023] Reference numerals: 100-Solar Cell; 1-base; 11- first surface; 111-Third District; 112-4th District; 12- second surface; 121-1st District; 122-Second District; 2-passivated contact structure; 21- tunneling oxide layer; 22-doped polysilicon layer; 23-polysilicon layer; 3-Emitter layer; 4-first electrode; 5- second electrode; 6-first passivation structure; 61-first passivation layer; 62-first anti-reflection layer; 7-second passivation structure; 71- second passivation layer; 72- second anti-reflection layer; 110-battery string; 120-encapsulation layer; 130-cover plate; Z-thickness direction.

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application. DETAILED DESCRIPTION

[0025] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0026] In the description of this application, unless otherwise specified or limited, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance; unless otherwise specified or explained, the term "plurality" refers to two or more; the terms "connected" and "fixed" should be understood in a broad sense. For example, "connected" can mean a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0027] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0028] It should be understood that the term "and / or" as used herein simply describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. Furthermore, the character " / " in this document generally indicates an "or" relationship between the associated objects.

[0029] It should be noted that the directional words such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described based on the angles shown in the accompanying drawings and should not be understood as limiting the embodiments of the present application. In addition, in the context, it should be understood that when it is mentioned that an element is connected to another element "on" or "under", it can not only be directly connected to the other element "on" or "under", but also be indirectly connected to the other element "on" or "under" through an intermediate element.

[0030] At present, in the preparation process of solar cells, it is usually necessary to first boron-diffusion on the front side of the solar cell substrate to form a whole layer of emitter layer, that is, the emitter layer covers the metal area and the non-metallic area, and then metallization treatment is performed on the metal area on the front side to form a metal electrode.

[0031] The emitter layer's resistance (i.e., boron diffusion square resistance) is used to quantify the emitter layer's doping concentration and conductivity. A higher square resistance indicates a lower boron doping concentration, better passivation, and a higher open-circuit voltage, which improves the solar cell's photovoltaic efficiency. However, excessively high square resistance in the metal region can lead to excessively high interface resistance between the metal electrode and emitter, reducing carrier collection efficiency and increasing series resistance, resulting in a lower fill factor. Furthermore, high contact resistance can easily induce carrier recombination, reducing the open-circuit voltage.

[0032] However, in the existing technology, the square resistance of the metal area cannot be further reduced, and the existing slurry cannot perfectly match the higher square resistance. That is, the interface contact resistance between the slurry and the high-square-resistance emitter layer is too high, and it is difficult for the metal electrode to form a good ohmic contact on the high-square-resistance emitter layer, which can easily affect the photoelectric conversion efficiency of the solar cell.

[0033] Based on this, the present application provides a method for preparing a solar cell, a solar cell, and a photovoltaic module to reduce the square resistance of the metal area and improve the photoelectric conversion efficiency of the solar cell. The solar cell can be applied to various battery structures, including but not limited to tunnel oxide passivated contact cells (TOPCon), etc., without limitation here. For example, the solar cell can specifically include a double-sided tunnel oxide passivated contact cell or a single-sided tunnel oxide passivated contact cell.

[0034] like Figure 1 As shown, the method for preparing the solar cell 100 provided in this application specifically includes the following steps: Step S1, preparing a substrate 1.

[0035] In this step, if Figure 2 As shown, substrate 1 is used to receive incident light and generate photogenerated carriers. In some embodiments, substrate 1 is a silicon substrate, which may include one or more of single crystal silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In other embodiments, the material of substrate 1 may also be silicon carbide, an organic material, or a multi-component compound. The multi-component compound may include, but is not limited to, perovskite, gallium arsenide, cadmium telluride, copper indium selenide, and the like. For example, in this application, substrate 1 is a single crystal silicon substrate.

[0036] Among them, Figure 2 As shown, the substrate 1 includes a first surface 11 and a second surface 12 that are opposite to each other along the thickness direction Z. For a monofacial cell, the second surface 12 of the substrate 1 can serve as the front surface, i.e., the light-receiving surface, and the first surface 11 of the substrate 1 can serve as the back surface, i.e., the backlight surface. For a bifacial cell, both the first surface 11 and the second surface 12 can serve as light-receiving surfaces to absorb incident light. The substrate 1 contains doping elements, and the doping element type can be N-type or P-type. N-type elements can be Group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As), while P-type elements can be Group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In). For example, when the substrate 1 is a P-type silicon substrate, the internal doping element type is P-type. For another example, when the substrate 1 is an N-type silicon substrate, the internal doping element type is N-type. For example, in the embodiment of the present application, the substrate 1 is an N-type silicon substrate to improve the conversion efficiency of the solar cell 100 and reduce manufacturing costs.

[0037] Step S2, such as Figure 3 As shown, a passivation contact structure 2 is formed on the first surface 11 of the substrate 1 .

[0038] In this step, if Figure 3As shown, the passivation contact structure 2 can provide good interface passivation for the first surface 11 of the solar cell, effectively reducing surface recombination and metal contact recombination.

[0039] It should be understood that in the preparation method provided in this embodiment, the process of preparing the passivation contact structure 2 on the first surface 11 of the substrate 1 is the same as the preparation method of the existing solar cell. For example, the passivation contact structure 2 can be the same as the back passivation contact structure of the existing TOPCon cell, specifically, as shown in FIG. Figure 3 As shown, the passivation contact structure 2 may include a tunneling oxide layer 21 and a doped polysilicon layer 22. Figure 4 and Figure 5 As shown, after a tunnel oxide layer 21 is deposited on the first surface 11 of the substrate 1, a polysilicon layer 23 can be deposited on the surface of the tunnel oxide layer 21 facing away from the substrate 1, and then the polysilicon layer 23 is doped with phosphorus diffusion to form a doped polysilicon layer 22. The detailed steps are described in detail later.

[0040] Before forming the passivation contact structure 2 on the first surface 11 of the substrate 1, alkaline back polishing, i.e., a back alkali polishing process, can be used to chemically corrode the first surface 11 of the substrate 1 using an alkaline solution (such as sodium hydroxide, sodium nitrate, sodium sulfate, hydrogen peroxide, etc.) to make the first surface 11 rough, thereby improving the efficiency of the solar cell 100 and reducing the preparation cost.

[0041] In addition, after forming the passivation contact structure 2 on the first surface 11 of the substrate 1, as shown in FIG. Figure 6 and Figure 7 As shown, a first passivation structure 6 can be formed on the first surface 11 side of the substrate 1, and a second passivation structure 7 can be formed on the second surface 12 side of the substrate 1, wherein the first passivation structure 6 includes a first passivation layer 61 and a first anti-reflection layer 62, and the second passivation structure 7 includes a second passivation layer 71 and a second anti-reflection layer 72. The detailed steps are described in detail later.

[0042] Step S3, such as Figure 8 As shown, a conductive paste is disposed on the first area 121 of the second surface 12 of the substrate 1 .

[0043] In this step, the second surface 12 of the substrate 1 has a first area 121 and a second area 122. A conductive paste can be applied to the first area 121 by screen printing. In other embodiments, the conductive paste can be applied to the first area 121 of the second surface 12 of the substrate 1 by laser transfer printing (LTP), inkjet printing, electroplating, aerosol jet printing, or direct writing to meet different preparation requirements. The specific application is not limited to this and can be adjusted based on actual needs.

[0044] Step S4, as Figure 8 As shown, the first region 121 is subjected to boron diffusion doping and sintering by laser, thereby forming the emitter layer 3 and the second electrode 5 in the first region 121 .

[0045] In this step, a laser is used to diffuse boron atoms in the first region 121 into the interior of the substrate 1 to form the emitter layer 3. Furthermore, a laser is used to sinter at least a portion of the conductive paste disposed on the first region 121 to form the second electrode 5. The emitter layer 3 and the substrate 1 have different doping elements, and together they form a PN junction structure, improving the efficiency of the solar cell 100. The second electrode 5 can directly or indirectly contact the emitter layer 3 to form an electrical connection. The second electrode 5 is used to collect and aggregate the current of the solar cell 100.

[0046] In this embodiment, Figure 8 As shown, boron diffusion doping is performed only in the first region 121 of the second surface 12 of the substrate 1 to form the emitter layer 3. The first region 121 of the second surface 12 of the substrate 1 has a high boron atom doping concentration and a low sheet resistance. This reduces the interface contact resistance between the second electrode 5 formed in the first region 121 and the emitter layer 3, allowing the second electrode 5 to form a good ohmic contact with the emitter layer 3, thereby improving carrier collection efficiency, reducing series resistance, lowering power loss within the battery, and improving the fill factor. Furthermore, reducing interface contact resistance can reduce carrier recombination and increase the open circuit voltage.

[0047] The second region 122 of the second surface 12 of the substrate 1 is not doped with boron atoms. The second region 122 of the second surface 12 of the substrate 1 is not doped with boron atoms, resulting in higher sheet resistance, lower Auger recombination, and better passivation effect, which can further increase the open circuit voltage of the solar cell 100.

[0048] Therefore, the solar cell 100 in the embodiment of the present application can have a lower square resistance in the first region 121 of the second surface 12 of the substrate 1, making it easier to match with the conductive paste, thereby enabling the second electrode 5 to form a good ohmic contact with the emitter layer 3, improving the carrier collection efficiency, while reducing the series resistance, and improving the fill factor and open-circuit voltage. At the same time, the second region 122 of the second surface 12 of the substrate 1 can have a higher square resistance, thereby having a better passivation effect, further improving the open-circuit voltage of the solar cell 100, thereby achieving simultaneous optimization of electrical contact performance and surface passivation effect, and improving the photoelectric conversion efficiency of the solar cell 100.

[0049] Furthermore, compared to conventional boron diffusion processes, laser boron diffusion doping more easily achieves higher concentrations of boron atoms, thereby making it easier to achieve lower sheet resistance in the first region 121 of the second surface 12 of the substrate 1, thereby facilitating matching with the conductive paste and further improving the photoelectric conversion efficiency of the solar cell 100. Furthermore, the solar cell fabrication method of the present application does not require a previous boron diffusion process, resulting in a simpler process flow and higher fabrication efficiency, which can reduce the cost of solar cell fabrication.

[0050] In a specific embodiment, the sheet resistance of the second region 122 of the second surface 12 of the solar cell 100 in the embodiment of the present application can be greater than 600Ω, thereby greatly reducing Auger recombination in this region, improving the passivation effect, reducing optical losses, and further increasing the open circuit voltage of the solar cell 100, which is beneficial to improving the photoelectric conversion efficiency of the solar cell 100.

[0051] In a specific embodiment, the conductive paste is boron silver paste.

[0052] In this embodiment, Figure 8 As shown, the conductive paste is a boron-silver paste, that is, the conductive paste contains both boron and silver. There is no need to print the boron paste and the silver paste in separate steps, which can further simplify the process flow and improve the preparation efficiency of solar cells. It is also convenient to use a laser to perform boron diffusion doping in the first area 121 in the subsequent process.

[0053] In another specific embodiment, the conductive paste is silver paste. Before forming the passivation contact structure 2 on the first surface 11 of the substrate 1 , the method for preparing the solar cell 100 further includes: disposing a boron paste on the first area 121 of the second surface 12 of the substrate 1 .

[0054] In this embodiment, Figure 8 As shown, the silver paste and the boron paste are disposed step by step in the first area 121 of the second surface 12 of the substrate 1 , which is more conducive to adjusting the printing parameters of the silver paste and the boron paste, thereby improving the preparation yield of the solar cell 100 .

[0055] The boron slurry can be provided in the first area 121 by screen printing. In some other embodiments, the boron slurry can also be provided in the first area 121 of the second surface 12 of the substrate 1 by laser transfer printing (LTP), inkjet printing, electroplating, aerosol jet printing, or direct writing, etc., to meet different preparation requirements. The specific setting can be based on actual needs, and this application does not impose any restrictions on this.

[0056] In a specific embodiment, the first region 121 is doped and sintered by laser to form the emitter layer 3 and the second electrode 5 in the first region 121, specifically comprising: using a first laser to simultaneously perform boron diffusion doping and sintering on the first region 121, and forming the second electrode 5 while forming the emitter layer 3 in the first region 121.

[0057] In this embodiment, Figure 8 As shown, laser doping and laser-assisted sintering are both performed within the first laser, so that the first laser can take into account the functions of doping and sintering, and can simultaneously dope the second surface 12 and the first region 121, so that boron atoms diffuse into the interior of the substrate 1 to form the emitter layer 3, and at least part of the slurry set on the first region 121 is sintered to form the second electrode 5, thereby eliminating the need to use multiple lasers for multiple operations, which can further simplify the process flow and improve the preparation efficiency of the solar cell 100.

[0058] In some implementations, the first laser can be switched to red and green light when doping the first region 121, and then switched to infrared light for sintering after effective doping. The first laser operation pattern has the same shape as the first region 121, thereby avoiding multiple laser operations on the first region 121 and improving the production efficiency of the solar cell 100. Furthermore, the parameters of the first laser during doping can be a laser power of 30% to 60%, a scanning speed of 40 km / s to 7040 km / s, and a laser spot of 50 μm to 200 μm. The parameters when switching to laser-assisted sintering after effective doping can be a laser power of 2% to 14%, a scanning speed of 40 km / s to 70 km / s, a laser spot of 50 μm to 200 μm, and a reverse voltage of 10V to 20V. The first laser operation pattern has the same shape as the first region 121. In some other embodiments, the first laser can also be other lasers that can take into account both laser doping and laser-assisted sintering. The specific settings can be based on actual needs and are not limited here.

[0059] In another specific embodiment, the first region 121 is doped and sintered by laser to form the emitter layer 3 and the second electrode 5 in the first region 121, which specifically includes: Step S41, as Figure 8 As shown, the first region 121 is doped with boron by diffusion using a second laser to form an emitter layer 3 in the first region 121 .

[0060] In this step, a second laser can be used to perform laser doping on the first area 121 of the second surface 12, so that boron atoms diffuse into the interior of the substrate 1, thereby forming the emitter layer 3 only in the first area 121. The second laser can be red or green light. Specifically, the parameters of the second laser can be a laser power of 30% to 60%, a scanning speed of 40 km / s to 7040 km / s, a laser spot of 50 μm to 200 μm, and the second laser operation pattern has the same shape as the first area 121. In some other embodiments, the second laser can also be other lasers capable of laser doping, such as red-nano laser, green laser, fiber laser, or ultraviolet laser, etc., which can be set according to actual needs and are not limited here.

[0061] In step S42 , the first region 121 is sintered by using a third laser to form a second electrode 5 in the first region 121 .

[0062] In this step, a third laser is used to sinter the first area 121, so that at least a portion of the conductive paste provided on the first area 121 is sintered to form the second electrode 5. The third laser can be infrared light. Specifically, the parameters of the third laser can be a laser power of 2% to 14%, a scanning speed of 40 km / s to 70 km / s, a laser spot of 50 μm to 200 μm, a reverse voltage of 10 V to 20 V, and the laser operation pattern is the same as the shape of the first area 121. The operation can also be performed on the entire surface. In some other embodiments, the third laser can also be other lasers capable of laser-assisted sintering, such as green light or ultraviolet light. The specific setting can be based on actual needs and is not limited here.

[0063] In this embodiment, the second laser and the third laser are used to perform laser doping and laser-assisted sintering on the first region 121 respectively, which can reduce the complexity of the laser, thereby reducing the difficulty of the process and making it easier to implement.

[0064] In another specific embodiment, a conductive paste is provided in the first region 121 of the second surface 12 of the substrate 1, and the first region 121 is subjected to boron diffusion doping and sintering by laser to form the emitter layer 3 and the second electrode 5 in the first region 121, specifically including: In step A1 , boron slurry is placed in the first area 121 .

[0065] In this step, the boron slurry can be provided in the first area 121 by screen printing. In some other embodiments, the boron slurry can also be provided in the first area 121 of the second surface 12 of the substrate 1 by laser transfer printing (LTP), inkjet printing, electroplating, aerosol jet printing, or direct writing, etc., to meet different preparation requirements. The specific setting can be based on actual needs and is not limited in this application.

[0066] In step A2 , a second laser is used to perform boron diffusion doping on the first region 121 to form an emitter layer 3 in the first region 121 .

[0067] In this step, a second laser can be used to perform laser doping on the first area 121 of the second surface 12, so that boron atoms diffuse into the interior of the substrate 1, thereby forming the emitter layer 3 only in the first area 121. The second laser can be red or green light. Specifically, the parameters of the second laser can be a laser power of 30% to 60%, a scanning speed of 40 km / s to 7040 km / s, a laser spot of 50 μm to 200 μm, and the second laser operation pattern has the same shape as the first area 121. In some other embodiments, the second laser can also be other lasers capable of laser doping, such as red-nano laser, green laser, fiber laser, or ultraviolet laser, etc., which can be set according to actual needs and are not limited here.

[0068] Step A3: placing silver paste in the first area 121 .

[0069] In this step, silver paste can be provided in the first area 121 by screen printing. In some other embodiments, silver paste can also be provided in the first area 121 of the second surface 12 of the substrate 1 by laser transfer printing (LTP), inkjet printing, electroplating, aerosol jet printing, or direct writing, etc., to meet different preparation requirements. The specific setting can be based on actual needs and is not limited in this application.

[0070] Step A4: Sintering the first region 121 with a third laser to form a second electrode 5 in the first region 121 .

[0071] In this step, a third laser is used to sinter the first area 121, so that at least a portion of the conductive paste provided on the first area 121 is sintered to form the second electrode 5. The third laser can be infrared light. Specifically, the parameters of the third laser can be a laser power of 2% to 14%, a scanning speed of 40 km / s to 70 km / s, a laser spot of 50 μm to 200 μm, a reverse voltage of 10 V to 20 V, and the laser operation pattern is the same as the shape of the first area 121. The operation can also be performed on the entire surface. In some other embodiments, the third laser can also be other lasers capable of laser-assisted sintering, such as green light or ultraviolet light. The specific setting can be based on actual needs and is not limited here.

[0072] In this embodiment, the silver paste and the boron paste are applied in stages to the first region 121 of the second surface 12 of the substrate 1. This facilitates adjustment of the printing parameters of the silver and boron pastes, thereby improving the yield rate of the solar cell 100. Furthermore, the use of a second laser and a third laser for laser doping and laser-assisted sintering of the first region 121, respectively, reduces the complexity of the lasers, thereby lowering the difficulty of the process and facilitating implementation.

[0073] It should be noted that, in the above embodiments, the paste used to form the second electrode 5 may also be one or more of aluminum, silver, gold, nickel, molybdenum or copper, which is not limited here.

[0074] In a specific embodiment, the passivation contact structure 2 is prepared on the first surface 11 of the substrate 1, specifically comprising: In step S21 , a tunneling oxide layer 21 is deposited on the first surface 11 of the substrate 1 .

[0075] In this step, a tunneling oxide layer 21 may be formed on the first surface 11 of the substrate 1 by using methods such as ozone oxidation, high-temperature thermal oxidation, nitric acid oxidation, chemical vapor deposition, and low-pressure chemical vapor deposition (LPCVD). The tunneling oxide layer 21 may include, but is not limited to, dielectric materials having a tunneling effect, such as silicon oxide, silicon oxynitride, intrinsic amorphous silicon, and intrinsic polycrystalline silicon. In the embodiment of the present application, the tunneling oxide layer 21 is silicon oxide to facilitate the preparation of the tunneling oxide layer 21.

[0076] like Figure 4As shown, the tunneling oxide layer 21 has a chemical passivation effect, providing good surface passivation for the first surface 11 of the substrate 1. By passivating the dangling bonds on the surface of the substrate 1, the tunneling oxide layer 21 can reduce the interface state density between the substrate 1 and the doped polysilicon layer, thereby allowing majority carriers (electrons) to tunnel into the doped polysilicon layer, while also preventing the recombination of minority carriers (holes). The tunneling oxide layer 21 can also widen the band gap, allowing majority carriers to be transported laterally in the doped polysilicon layer and collected by the metal electrode, thereby greatly reducing the metal contact recombination current and improving the open circuit voltage and short circuit current of the battery. The tunneling oxide layer 21 also has a blocking effect, preventing the subsequent polysilicon layer from growing into the substrate 1. It can also prevent the doping elements doped in the polysilicon layer from diffusing into the substrate 1, reducing the impurity content in the substrate 1 and improving the efficiency of the solar cell 100.

[0077] In step S22 , a polysilicon layer 23 is deposited on the surface of the tunnel oxide layer 21 facing away from the substrate 1 .

[0078] In this step, if Figure 5 As shown, any one of physical vapor deposition, chemical vapor deposition, plasma enhanced chemical vapor deposition, and atomic layer deposition can be used to deposit a polysilicon layer 23 on the surface of the tunnel oxide layer 21. For example, low pressure chemical vapor deposition (LPCVD) can be used to deposit the polysilicon layer 23 on the surface of the tunnel oxide layer 21 away from the substrate 1. Silane is introduced into the LPCVD machine, and amorphous silicon grows and nucleates on the side of the tunnel oxide layer 21 away from the substrate 1, and finally forms crystals, thereby forming a polysilicon layer 23. The polysilicon layer 23 is formed on the side of the tunnel oxide layer 21 away from the substrate 1, so that the polysilicon layer 23 and the tunnel oxide layer 21 together form a passivation contact structure, further improving the passivation effect of the first surface 11.

[0079] Among them, there are mainly two processes for preparing the polysilicon layer 23 on the tunneling oxide layer 21 by LPCVD, namely single insertion and double insertion. The specific process can be selected according to actual needs and is not limited here. Specifically, single insertion means inserting a substrate 1 in a LPCVD quartz boat, that is, preparing a polysilicon layer 23 on both the first surface 11 side and the second surface 12 side of the substrate 1. However, since the second surface 12 side of the single-sided tunneling oxide passivation contact cell does not require a polysilicon layer 23, the polysilicon layer 23 on the second surface 12 side can be cleaned and removed when preparing the single-sided tunneling oxide passivation contact cell. Double insertion means inserting two substrates 1 in a LPCVD quartz boat so that the second surfaces 12 of the two substrates 1 that do not need to prepare the polysilicon layer 23 are in contact with each other, so that the first surfaces 11 sides of the two substrates 1 that need to prepare the polysilicon layer 23 are outward, and the polysilicon layer 23 is only prepared on the first surface 11 side of the substrate 1, which further improves the preparation efficiency.

[0080] In step S23 , phosphorus diffusion doping is performed on the polysilicon layer 23 to form a doped polysilicon layer 22 .

[0081] In this step, if Figure 5 As shown, phosphorus is doped into the polysilicon layer 23 to form Figure 3 The doped polysilicon layer 22 shown is configured so that the doping element in the doped polysilicon layer 22 is the same as that in the substrate 1, thereby forming a doping element concentration difference between the doped polysilicon layer 22 and the substrate 1, thereby forming a potential barrier, so that electrons in the substrate 1 can jump to the metal electrode and be collected by the metal electrode, so that the doped polysilicon layer 22 can form good contact with the metal electrode, which is beneficial to the transmission of electrons, thereby improving the open circuit voltage of the solar cell 100, and thus improving the photoelectric conversion efficiency of the solar cell 100.

[0082] In the method for preparing the solar cell 100 , the specific operation mode of the phosphorus diffusion process is not limited, and conventional technical means can be used, which is not limited here.

[0083] It should be noted that after forming the doped polysilicon layer 22 , the wrap-around plating located on the second surface 12 side of the substrate 1 needs to be removed. The specific removal process can adopt existing methods known to those skilled in the art and will not be described in detail here.

[0084] In this embodiment, the main function of the tunneling oxide layer 21 is to serve as a tunneling layer for majority carriers. At the same time, it can chemically passivate the surface of the substrate 1, reduce the interface state density, thereby allowing majority carriers to tunnel into the doped polysilicon layer 22, and at the same time prevent the recombination of minority carriers. The doped polysilicon layer 22 is arranged on the side of the tunneling oxide layer 21 away from the substrate 1. The doped polysilicon layer 22 can serve as a field passivation layer. The doped polysilicon layer 22 and the tunneling oxide layer 21 together form a passivation contact structure, which further enhances the passivation effect on the surface of the substrate 1. The doping elements in the doped polysilicon layer 22 are the same as those in the substrate 1, and a concentration difference is formed between the doped polysilicon layer 22 and the substrate 1, so that the doped polysilicon layer 22 can form a good contact with the metal electrode and can form a band bending on the surface of the substrate 1, thereby realizing the selective transmission of carriers and reducing recombination losses.

[0085] In a specific embodiment, Figure 8 As shown, after the passivation contact structure 2 is prepared on the first surface 11 of the substrate 1 , the method for preparing the solar cell 100 further includes: performing metallization treatment on the side of the doped polysilicon layer 22 facing away from the tunneling oxide layer 21 to form a first electrode 4 .

[0086] The first electrode 4 is used to collect and aggregate the current of the solar cell 100. For example, the first electrode 4 can be formed on the surface of the doped polysilicon layer 22 facing away from the tunneling oxide layer 21 by screen printing and sintering, so that the first electrode 4 is electrically connected to the doped polysilicon layer 22. The metal paste used to prepare the first electrode 4 can be one or more of aluminum, silver, gold, nickel, molybdenum, or copper, without limitation.

[0087] Specifically, a metallization process is performed on the side of the doped polysilicon layer 22 facing away from the tunneling oxide layer 21 to form the first electrode 4. Specifically, a slurry is placed on the side of the doped polysilicon layer 22 facing away from the tunneling oxide layer 21, and then laser-assisted sintering is performed to form the first electrode 4. In this step, the laser-assisted sintering to form the first electrode 4 can be performed simultaneously with the above-mentioned sintering of the first region 121 using the third laser to form the second electrode 5 in the first region 121, thereby further simplifying the process flow and improving the production efficiency of the solar cell 100.

[0088] In a specific implementation, after the passivation contact structure 2 is prepared on the first surface 11 of the substrate 1, the method for preparing the solar cell 100 further includes: Step B1, such as Figure 6 As shown, the passivation contact structure 2 in the fourth region 112 of the first surface 11 is removed.

[0089] In this step, phosphosilicate glass (PSG) is produced during the preparation of the passivation contact structure 2. Exemplarily, the PSG in the fourth region 112 of the first surface 11 can be first removed by back laser, and then the PSG in the third region 111 of the first surface 11 and the passivation contact structure 2 in the fourth region 112 can be removed together by texturing or positive etching, thereby retaining the passivation contact structure only in the third region 111 of the first surface 11. Exemplarily, hydrofluoric acid (HF) can be used to clean the PSG on the first surface 11 first, and then the passivation contact structure 2 in the fourth region 112 of the first surface 11 can be removed by back laser and texturing, thereby retaining the passivation contact structure only in the third region 111 of the first surface 11. Exemplarily, the passivation contact structure 2 in the fourth region 112 of the first surface 11 can also be directly removed by positive etching, thereby retaining the passivation contact structure only in the third region 111 of the first surface 11. Of course, the passivation contact structure 2 in the fourth area 112 of the first surface 11 may also be removed by other methods, which may be configured according to actual needs and are not limited here.

[0090] In this embodiment, Figures 6 to 8 As shown, by removing the passivation contact structure 2 in the fourth area 112 of the first surface 11, the passivation contact structure 2 is retained only in the third area 111 of the first surface 11, thereby forming a Figure 8 The solar cell 100 structure shown in FIG. The provision of a passivation contact structure 2 in the third region 111 of the first surface 11 enables a first electrode subsequently disposed on the third region 111 to form good ohmic contact therewith, thereby improving carrier collection efficiency, reducing contact resistance, and increasing the fill factor. Removing the passivation contact structure 2 in the fourth region 112 of the first surface 11 can enhance the passivation effect of the fourth region 112 of the first surface 11 and reduce optical loss. Therefore, by removing the passivation contact structure 2 in the fourth region 112 of the first surface 11, thereby retaining the passivation contact structure only in the third region 111 of the first surface 11, both electrical contact performance and surface passivation can be optimized, thereby improving the photoelectric conversion efficiency of the solar cell 100.

[0091] In a specific embodiment, after the passivation contact structure 2 is formed on the first surface 11 of the substrate 1, the method for preparing the solar cell 100 further includes: Step B2, such as Figure 7 As shown, a first passivation structure 6 is formed on the side of the passivation contact structure 2 facing away from the substrate 1 and on the first surface 11 of the substrate 1 , and a second passivation structure 7 is formed on the second surface 12 of the substrate 1 .

[0092] In this step, the first passivation structure 6 and the second passivation structure 7 may be deposited by plasma enhanced chemical vapor deposition. Of course, other methods such as organic chemical vapor deposition may also be used to form the first passivation structure 6 and the second passivation structure 7.

[0093] In this embodiment, Figure 7 and Figure 8 As shown, the first passivation structure 6 can form a good passivation effect on the first surface 11 of the substrate 1 and the side of the passivation contact structure 2 facing away from the substrate 1, and the second passivation structure 7 can form a good passivation effect on the second surface 12 of the substrate 1, which is beneficial to improving the photoelectric conversion efficiency of the solar cell 100.

[0094] In another specific embodiment, after forming the passivation contact structure 2 on the first surface 11 of the substrate 1 , the method for preparing the solar cell 100 further includes: In step C1 , a first passivation structure 6 is formed on the side of the passivation contact structure 2 facing away from the substrate 1 , and a second passivation structure 7 is formed on the second surface 12 of the substrate 1 .

[0095] In this step, the first passivation structure 6 and the second passivation structure 7 may be deposited by plasma enhanced chemical vapor deposition. Of course, other methods such as organic chemical vapor deposition may also be used to form the first passivation structure 6 and the second passivation structure 7.

[0096] In this embodiment, Figure 9 and Figure 10 As shown, the first passivation structure 6 is formed directly on the side of the passivation contact structure 2 facing away from the substrate 1, and the second passivation structure 7 is formed on the second surface 12 of the substrate 1. Figure 10 The solar cell 100 structure shown in FIG. The first passivation structure 6 can effectively passivate the side of the passivation contact structure 2 facing away from the substrate 1, and the second passivation structure 7 can effectively passivate the second surface 12 of the substrate 1, thereby improving the photoelectric conversion efficiency of the solar cell 100. Furthermore, since there is no need to remove at least a portion of the passivation contact structure 2 on the first surface 11, the process flow can be further simplified, thereby improving the production efficiency of the solar cell 100.

[0097] In a specific embodiment, Figures 7 to 10 As shown, the first passivation structure 6 includes a first passivation layer 61 and a first anti-reflection layer 62 .

[0098] The first passivation layer 61 can produce a good passivation effect on the substrate 1, which helps to improve the conversion efficiency of the solar cell 100. In some embodiments, the back passivation layer can be deposited by plasma enhanced chemical vapor deposition. Of course, other methods can also be used, such as organic chemical vapor deposition, to form the first passivation layer 61 on the surface of the doped polysilicon layer 22 away from the tunneling oxide layer and / or the first surface 11 of the substrate 1, wherein the first passivation layer 61 can be a single layer structure or a stacked layer structure. The first passivation layer 61 can be a combination of any one or more of a silicon nitride layer, a silicon oxynitride layer, and an aluminum oxide layer. Of course, the first passivation layer 61 can also use other types of passivation layers. This application does not limit the specific material of the first passivation layer 61. For example, when the first passivation layer 61 is an aluminum oxide layer, the first passivation layer 61 can be deposited using atomic layer deposition (ALD) technology to improve the preparation efficiency of the solar cell and save costs.

[0099] The first anti-reflection layer 62 is disposed on the surface of the first passivation layer 61 facing away from the substrate 1, and can reduce or eliminate reflected light from the surface of the solar cell 100 and increase light transmittance, thereby improving the photoelectric conversion efficiency of the solar cell. The first anti-reflection layer 62 can be a silicon nitride layer, thereby further reducing the difficulty of manufacturing the solar cell 100 and improving manufacturing efficiency. Of course, the first anti-reflection layer 62 can also be a silicon oxynitride layer, or a single layer or stacked layer structure composed of silicon nitride and silicon oxynitride, or can also be other anti-reflection film layer structures, without limitation herein.

[0100] In a specific embodiment, Figures 7 to 10 As shown, the second passivation structure 7 includes a second passivation layer 71 and a second anti-reflection layer 72 .

[0101] The second passivation layer 71 can produce a good passivation effect on the substrate 1, which helps to improve the conversion efficiency of the solar cell 100. In some embodiments, the back passivation layer can be deposited by plasma enhanced chemical vapor deposition. Of course, other methods can also be used, such as organic chemical vapor deposition, to form the second passivation layer 71 on the surface of the doped polysilicon layer 22 away from the tunneling oxide layer and / or the first surface 11 of the substrate 1, wherein the second passivation layer 71 can be a single layer structure or a stacked layer structure. The second passivation layer 71 can be a combination of any one or more of a silicon nitride layer, a silicon oxynitride layer, and an aluminum oxide layer. Of course, the second passivation layer 71 can also use other types of passivation layers. This application does not limit the specific material of the second passivation layer 71. For example, when the second passivation layer 71 is an aluminum oxide layer, the second passivation layer 71 can be deposited using atomic layer deposition (ALD) technology to improve the preparation efficiency of the solar cell and save costs.

[0102] The second anti-reflection layer 72 is disposed on the surface of the second passivation layer 71 facing away from the substrate 1, and can reduce or eliminate reflected light from the surface of the solar cell 100 and increase light transmittance, thereby improving the photoelectric conversion efficiency of the solar cell. The second anti-reflection layer 72 can be a silicon nitride layer, thereby further reducing the difficulty of manufacturing the solar cell 100 and improving the manufacturing efficiency. Of course, the second anti-reflection layer 72 can also be a silicon oxynitride layer, or a single layer or stacked layer structure composed of silicon nitride and silicon oxynitride, or can also be other anti-reflection film layer structures, without limitation herein.

[0103] The embodiment of the present application also provides a solar cell 100, such as Figure 8 and Figure 10 As shown, the solar cell 100 is prepared by the method for preparing a solar cell in any of the above embodiments, and specifically includes a substrate 1, a passivation contact structure 2, an emitter layer 3, and a second electrode 5. The substrate 1 includes a first surface 11 and a second surface 12, the passivation contact structure 2 is provided on the first surface 11, the emitter layer 3 is provided in the first region 121 of the second surface 12, and the second electrode 5 is provided on a side of the emitter layer 3 facing away from the substrate 1 and is electrically connected to the emitter layer 3.

[0104] The substrate 1 is used to receive incident light and generate photogenerated carriers. In some embodiments, the substrate 1 is a silicon substrate, which may include one or more of single crystal silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In other embodiments, the material of the substrate 1 may also be silicon carbide, an organic material, or a multi-component compound. The multi-component compound may include, but is not limited to, perovskite, gallium arsenide, cadmium telluride, copper indium selenide, and the like. For example, in the present application, the substrate 1 is a single crystal silicon substrate. The substrate 1 includes a first surface 11 and a second surface 12 that are opposite to each other along the thickness direction Z. For a single-sided cell, the second surface 12 of the substrate 1 may serve as the front side, i.e., the light-receiving side, and the first surface 11 of the substrate 1 may serve as the back side, i.e., the backlight side; for a double-sided cell, both the first surface 11 and the second surface 12 may serve as the light-receiving side to absorb incident light. The substrate 1 contains doping elements, and the doping element type can be N-type or P-type. The N-type element can be a Group V element such as phosphorus (P), bismuth (Bi), antimony (Sb) or arsenic (As), and the P-type element can be a Group III element such as boron (B), aluminum (Al), gallium (Ga) or indium (In). For example, when the substrate 1 is a P-type silicon substrate, the type of doping element inside it is P-type. For another example, when the substrate 1 is an N-type silicon substrate, the type of doping element inside it is N-type. For example, in the embodiment of the present application, the substrate 1 is an N-type silicon substrate to improve the conversion efficiency of the solar cell 100 and reduce the manufacturing cost.

[0105] The passivation contact structure 2 can provide good interface passivation for the first surface 11 of the solar cell, effectively reducing surface recombination and metal contact recombination. Specifically, the passivation contact structure 2 can include a tunneling oxide layer 21 and a doped polysilicon layer 22.

[0106] The emitter layer 3 and the substrate 1 have different doping element types, and the two can together form a PN junction structure to improve the efficiency of the solar cell 100 .

[0107] The second electrode 5 can be in direct or indirect contact with the emitter layer 3 to form an electrical connection structure. The second electrode 5 is used to collect and aggregate the current of the solar cell 100 .

[0108] In this embodiment, Figure 8 and Figure 10 As shown, boron diffusion doping is performed only in the first region 121 of the second surface 12 of the substrate 1 to form the emitter layer 3. The first region 121 of the second surface 12 of the substrate 1 has a high boron atom doping concentration and a low sheet resistance. This reduces the interface contact resistance between the second electrode 5 formed in the first region 121 and the emitter layer 3, allowing the second electrode 5 to form a good ohmic contact with the emitter layer 3, thereby improving carrier collection efficiency, reducing series resistance, lowering power loss within the battery, and improving the fill factor. Furthermore, reducing interface contact resistance can reduce carrier recombination and increase the open circuit voltage.

[0109] The second region 122 of the second surface 12 of the substrate 1 is not doped with boron atoms. The second region 122 of the second surface 12 of the substrate 1 is not doped with boron atoms, resulting in higher sheet resistance, lower Auger recombination, and better passivation effect, which can further increase the open circuit voltage of the solar cell 100.

[0110] Therefore, the solar cell 100 in the embodiment of the present application can have a lower square resistance in the first region 121 of the second surface 12 of the substrate 1, making it easier to match with the conductive paste, thereby enabling the second electrode 5 to form a good ohmic contact with the emitter layer 3, improving the carrier collection efficiency, while reducing the series resistance, and improving the fill factor and open-circuit voltage. At the same time, the second region 122 of the second surface 12 of the substrate 1 can have a higher square resistance, thereby having a better passivation effect, further improving the open-circuit voltage of the solar cell 100, thereby achieving simultaneous optimization of electrical contact performance and surface passivation effect, and improving the photoelectric conversion efficiency of the solar cell 100.

[0111] Furthermore, compared to conventional boron diffusion processes, laser boron diffusion doping more easily achieves higher concentrations of boron atoms, thereby making it easier to achieve lower sheet resistance in the first region 121 of the second surface 12 of the substrate 1, thereby facilitating matching with the conductive paste and further improving the photoelectric conversion efficiency of the solar cell 100. Furthermore, the solar cell fabrication method of the present application does not require a previous boron diffusion process, resulting in a simpler process flow and higher fabrication efficiency, which can reduce the cost of solar cell fabrication.

[0112] In addition, the solar cell 100 may further include a first passivation structure 6 , a second passivation structure 7 and a first electrode 4 .

[0113] The first electrode 4 is disposed on a surface of the doped polysilicon layer 22 facing away from the tunneling oxide layer 21. The first electrode 4 is used to collect and aggregate the current of the solar cell 100. For example, the first electrode 4 can be formed on a surface of the doped polysilicon layer 22 facing away from the tunneling oxide layer 21 by screen printing and sintering, electrically connecting the first electrode 4 to the doped polysilicon layer 22. The metal paste used to prepare the first electrode 4 can be one or more of aluminum, silver, gold, nickel, molybdenum, or copper, without limitation.

[0114] The first passivation structure 6 is provided on the side of the passivation contact structure 2 facing away from the substrate 1 and / or the first surface 11 of the substrate 1. Specifically, the first passivation structure 6 includes a first passivation layer 61 and a first anti-reflection layer 62. The first passivation layer 61 can produce a good passivation effect on the substrate 1, which helps to improve the conversion efficiency of the solar cell 100. In some embodiments, a plasma-enhanced chemical vapor deposition method can be used to deposit the back passivation layer. Of course, other methods can also be used, such as organic chemical vapor deposition, to form the first passivation layer 61 on the surface of the doped polysilicon layer 22 facing away from the tunneling oxide layer and / or the first surface 11 of the substrate 1, wherein the first passivation layer 61 can be a single-layer structure or a stacked-layer structure. The first passivation layer 61 can be a combination of any one or more of a silicon nitride layer, a silicon oxynitride layer, and an aluminum oxide layer. Of course, the first passivation layer 61 can also be other types of passivation layers, and the present application does not limit the specific material of the first passivation layer 61. For example, when the first passivation layer 61 is an aluminum oxide layer, the first passivation layer 61 can be deposited using atomic layer deposition (ALD) technology to improve the production efficiency of the solar cell and save costs. The first anti-reflection layer 62 is arranged on the surface of the first passivation layer 61 facing away from the substrate 1, which can reduce or eliminate the reflected light on the surface of the solar cell 100 and increase the amount of light transmitted, thereby improving the photoelectric conversion efficiency of the solar cell. Among them, the first anti-reflection layer 62 can be a silicon nitride layer, which can further reduce the difficulty of preparing the solar cell 100 and improve the production efficiency. Of course, the first anti-reflection layer 62 can also be a silicon oxynitride layer or a single layer or stacked layer structure composed of silicon nitride and silicon oxynitride, or it can also be other anti-reflection film layer structures, which are not limited here.

[0115] The second passivation structure 7 is provided on the second surface 12 of the substrate 1. Specifically, the second passivation structure 7 includes a second passivation layer 71 and a second anti-reflection layer 72. The second passivation layer 71 can produce a good passivation effect on the substrate 1, which helps to improve the conversion efficiency of the solar cell 100. In some embodiments, a plasma-enhanced chemical vapor deposition method can be used to deposit the back passivation layer. Of course, other methods can also be used, such as organic chemical vapor deposition, etc. to form the second passivation layer 71 on the surface of the doped polysilicon layer 22 away from the tunneling oxide layer and / or the first surface 11 of the substrate 1, wherein the second passivation layer 71 can be a single-layer structure or a stacked-layer structure, and the second passivation layer 71 can be a combination of any one or more of a silicon nitride layer, a silicon oxynitride layer, and an aluminum oxide layer. Of course, the second passivation layer 71 can also be other types of passivation layers, and the present application does not limit the specific material of the second passivation layer 71. For example, when the second passivation layer 71 is an aluminum oxide layer, the second passivation layer 71 can be deposited using atomic layer deposition (ALD) technology to improve the production efficiency of the solar cell and save costs. The second anti-reflection layer 72 is arranged on the surface of the second passivation layer 71 facing away from the substrate 1, which can reduce or eliminate the reflected light on the surface of the solar cell 100 and increase the amount of light transmitted, thereby improving the photoelectric conversion efficiency of the solar cell. Among them, the second anti-reflection layer 72 can be a silicon nitride layer, which can further reduce the difficulty of preparing the solar cell 100 and improve the production efficiency. Of course, the second anti-reflection layer 72 can also be a silicon oxynitride layer or a single layer or stacked layer structure composed of silicon nitride and silicon oxynitride, or it can also be other anti-reflection film layer structures, which are not limited here.

[0116] The present application also provides a photovoltaic module, such as Figure 11 As shown, the photovoltaic module includes a cell string 110, an encapsulation layer 120, and a cover plate 130. The cell string 110 is formed by connecting multiple solar cells 100 as in any of the above embodiments. The encapsulation layer 120 is used to cover the surface of the cell string 110, and the cover plate 130 is used to cover the surface of the encapsulation layer 120 away from the cell string 110. Since the solar cell 100 has the above technical effects, the photovoltaic module including the solar cell 100 should also have the above technical effects, which will not be described in detail here.

[0117] Among them, Figure 5As shown, solar cells 100 are electrically connected in whole or multiple sections to form multiple cell strings 110. Multiple cell strings 110 are electrically connected in series and / or in parallel. Specifically, multiple cell strings 110 can be electrically connected via conductive tape. An encapsulation layer 120 covers the front and back sides of the solar cell. Specifically, encapsulation layer 120 can be an organic encapsulation film such as ethylene-vinyl acetate (EVA) film, polyethylene-octene co-elastomer (POE) film, polyethylene terephthalate (PET) film, or polyvinyl butyral (PVB). Cover plate 130 can be a light-transmitting cover plate 130 such as a glass cover plate or a plastic cover plate. Specifically, the surface of cover plate 130 facing encapsulation layer 120 can have a concave-convex surface to increase the utilization of incident light.

[0118] In this specification, reference can be made to the same or similar parts between the various embodiments. In particular, for the device embodiment and the terminal embodiment, since they are basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the description in the method embodiment.

[0119] The above description is merely a specific implementation of the embodiments of the present application, but the scope of protection of the embodiments of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of the present application shall be included in the scope of protection of the embodiments of the present application. Therefore, the scope of protection of the embodiments of the present application shall be based on the scope of protection of the claims.

Claims

1. A method for preparing a solar cell, characterized in that: The method for preparing the solar cell (100) specifically comprises the following steps: preparing a substrate (1); forming a passivation contact structure (2) on the first surface (11) of the substrate (1); Disposing a conductive paste in a first area (121) of the second surface (12) of the substrate (1); The first region (121) is subjected to boron diffusion doping and sintering by laser, thereby forming an emitter layer (3) and a second electrode (5) in the first region (121).

2. The method for preparing a solar cell according to claim 1, wherein: The conductive paste is boron silver paste.

3. The method for preparing a solar cell according to claim 1, wherein: The conductive paste is silver paste; Before preparing the passivation contact structure (2) on the first surface (11) of the substrate (1), the method for preparing the solar cell (100) further comprises: providing a boron paste in the first area (121) of the second surface (12) of the substrate (1).

4. The method for preparing a solar cell according to claim 2 or 3, characterized in that: The method of doping and sintering the first region (121) with a laser to form an emitter layer (3) and a second electrode (5) in the first region (121) specifically includes: The first region (121) is simultaneously subjected to boron diffusion doping and sintering using a first laser, and a second electrode (5) is formed while an emitter layer (3) is formed in the first region (121).

5. The method for preparing a solar cell according to claim 2 or 3, characterized in that: The method of doping and sintering the first region (121) with a laser to form an emitter layer (3) and a second electrode (5) in the first region (121) specifically includes: Using a second laser to perform boron diffusion doping on the first region (121) to form an emitter layer (3) in the first region (121); The first region (121) is sintered using a third laser to form a second electrode (5) in the first region (121).

6. The method for preparing a solar cell according to claim 1, wherein: The method comprises providing a conductive paste in a first area (121) of the second surface (12) of the substrate (1), doping and sintering the first area (121) with a laser, and forming an emitter layer (3) and a second electrode (5) in the first area (121), specifically comprising: providing a boron slurry in the first zone (121); Using a second laser to perform boron diffusion doping on the first region (121) to form an emitter layer (3) in the first region (121); Arranging silver paste in the first area (121); The first region (121) is sintered using a third laser to form a second electrode (5) in the first region (121).

7. The method for preparing a solar cell according to claim 1, wherein: The process of preparing a passivation contact structure (2) on the first surface (11) of the substrate (1) specifically comprises: Depositing a tunneling oxide layer (21) on the first surface (11) of the substrate (1); Depositing a polysilicon layer (23) on a surface of the tunnel oxide layer (21) facing away from the substrate (1); Phosphorus diffusion doping is performed on the polysilicon layer (23) to form a doped polysilicon layer (22).

8. The method for preparing a solar cell according to claim 7, wherein: After preparing the passivation contact structure (2) on the first surface (11) of the substrate (1), the method for preparing the solar cell (100) further comprises: A metallization process is performed on a side of the doped polysilicon layer (22) facing away from the tunneling oxide layer (21) to form a first electrode (4).

9. The method for preparing a solar cell according to claim 1, wherein: After preparing the passivation contact structure (2) on the first surface (11) of the substrate (1), the method for preparing the solar cell (100) further comprises: The passivation contact structure (2) of the fourth region (112) of the first surface (11) is removed.

10. The method for preparing a solar cell according to claim 9, wherein: After preparing the passivation contact structure (2) on the first surface (11) of the substrate (1), the method for preparing the solar cell (100) further comprises: A first passivation structure (6) is formed on the side of the passivation contact structure (2) facing away from the substrate (1) and on the first surface (11) of the substrate (1), and a second passivation structure (7) is formed on the second surface (12) of the substrate (1).

11. The method for preparing a solar cell according to claim 1, wherein: After preparing the passivation contact structure (2) on the first surface (11) of the substrate (1), the method for preparing the solar cell (100) further comprises: A first passivation structure (6) is formed on the side of the passivation contact structure (2) facing away from the substrate (1), and a second passivation structure (7) is formed on the second surface (12) of the substrate (1).

12. A solar cell, characterized in that: The solar cell (100) is prepared by the method for preparing a solar cell according to any one of claims 1 to 11, specifically comprising: A substrate (1), the substrate (1) comprising a first surface (11) and a second surface (12); a passivation contact structure (2), the passivation contact structure (2) being arranged on the first surface (11); an emitter layer (3), the emitter layer (3) being arranged in a first region (121) of the second surface (12); A second electrode (5), the second electrode (5) is arranged on a side of the emitter layer (3) facing away from the substrate (1), and is electrically connected to the emitter layer (3).

13. A photovoltaic module, characterized in that: The photovoltaic module comprises: A battery string (110), wherein the battery string (110) is formed by connecting a plurality of solar cells (100) as claimed in claim 12; an encapsulation layer (120), the encapsulation layer (120) being used to cover the surface of the battery string (110); A cover plate (130) is used to cover a surface of the packaging layer (120) away from the battery string (110).

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